Persons with limited mobility, such as the elderly or persons confined to a wheelchair are susceptible to the development of pressure sores. Pressure sores are formed when the tissue is compressed for extended periods of time causing a restriction in the flow of blood. The exchange of nutrients and waste in the compressed tissue cells is slowed, resulting in skin breakdown and the formation of pressure sores. The retention of heat and moisture are two additional factors that contribute to the formation of pressure sores. Areas most vulnerable to pressure sore formation are bony areas having little tissue between the bone and the skin, including such areas as the ischial tuberosities, coccyx and sacrum.
U.S. Pat. No. 6,216,299 discloses a wheelchair cushion system wherein the cushion includes an array of inflatable square pockets including first and second interconnected groupings of pockets interspersed throughout the array which are independently inflated and deflated on a predetermined schedule in order to vary the location of contact between the cushion and the body of a person seated on the cushion.
While providing a significant advance in efforts to reduce the development of pressure sores on persons confined to wheel chairs, pressure sores remain a persistent problem for those with limited mobility and a continuing need exists for further improvements in devices capable of reducing or eliminating the development of pressure sores caused by daily prolonged seating.
The invention is a cushion having a plurality of inflatable and deflatable cells useful for periodically shifting the points of contact between the cushion and a body supported by the cushion in order to reduce or eliminate the development of pressure sores.
A first embodiment of the cushion has at least two encircling cells shaped so as to define a central concavity in the upper surface of each of the encircling cells.
A second embodiment of the cushion has at least one cell repositionably attached to the first major surface of a base for allowing repositioning of the cell on the base. It is generally preferred that at least one of the encircling cells is repositionably attached to the first major surface of the base. Such repositionability of the cells allows positioning of the cells to correspond with the location of one of more of the ischial tuberosities, coccyx, and sacrum of each specific user and thereby provide appropriate pressure relief.
A third embodiment of the cushion has at least two contoured cells with each contoured cell independently defining a longitudinally extending laterally concave channel on the upper surface of the contoured cell.
A fourth embodiment of the cushion has a majority of the cells symmetrically configured and arranged on opposite sides of a central longitudinal axis wherein (i) a first set of the symmetrically configured and arranged cells are jointly inflatable and deflatable, (ii) a second set of the symmetrically configured and arranged cells are jointly inflatable and deflatable, and (iii) the first set of jointly inflatable and deflatable cells are asymmetrically configured and arranged relative to the second set of jointly inflatable and deflatable cells on opposite sides of the central longitudinal axis.